1. Modified version of operational Lacis-Hansen scheme with
modified water & ice absorption coefficients that are
more consistent with those in the GFS radiation scheme

2. In calculating solar absorption, the optical depths for
cloud water and for ice (cloud ice and snow) are obtained using the
relationships described by eqs. (5.2), (5.3), and Table 9 from
Hou et al. (2002), assuming a constant effective radius of 10 microns
for cloud water and 75 microns for ice. For cloud water optical depths,
equal weighting is assumed for absorption of UV-VIS and near IR radiation.

3. A minimum optical depth is
assumed for grid-scale liquid water clouds consistent with a minimum
mixing ratio of 0.1 g/kg. This lower limit has been removed, and this
change has been found to have the biggest impact.

A number of changes have been made to the Noah land-surface model (LSM)
used in the operational mesoscale Eta model, from the previous version
(2.3.2) to the current version (2.7). These involve changes to Noah LSM
physics, model formulation parameters, and some additional numerical
refinements.
Also, removing
the vegetation greenness factor from the snow albedo formulation leads
to an increase in albedo under snow-covered conditions. The Eta model
cloud microphysics now passes the fraction of frozen precipitation to
the Noah LSM, eliminating the crude determination of frozen
precipitation by the Noah LSM based on lowest (atmospheric) model level
air temperature. Separate snow sublimation and non-snow-covered
evaporation is now considered for patchy snow cover conditions when
snowpack is shallow, reducing snow sublimation and snowpack depletion.
Changes to parameters in the patchy snow cover formulation decrease the
snow depth for 100 percent snow cover. A reduction in
vegetation-dependent soil moisture threshold values will increase
transpiration. The depth at which the lower boundary condition on soil
temperature is applied is increased from 3 meters to 8 meters. The
thermal heat capacity of mineral soil has been changed to a more
standard value. A change to the coefficient in the thermal-roughness
length calculation will decrease the surface skin-atmosphere temperature
gradient. The sea-ice albedo is changed from 0.60 to 0.65. Including a
diagnostic soil heat flux calculation at the end of the Noah LSM code
leads to better closure of the surface energy budget.

Parameter SMHIGH_DATA reduced from 6.0 to 3.0; this will raise the value of the
reference soil moisture value below which vegetation becomes stressed (SMCREF),
which (at first order) should reduce the transpiration (surface moisture flux).

Minimum stomatal conductance increased from 40s/m to 70s/m for
cropland, pasture, and grassland vegetation types in order to decrease
surface evaporation.

The hi-res soil and vegetation type classifications:

CLASS USGS-WRF VEGETATION/SURFACE TYPE

Urban and Built-Up Land

Dryland Cropland and Pasture

Irrigated Cropland and Pasture

Mixed Dryland/Irrigated Cropland and Pasture

Cropland/Grassland Mosaic

Cropland/Woodland Mosaic

Grassland

Shrubland

Mixed Shrubland/Grassland

Savanna

Deciduous Broadleaf Forest

Deciduous Needleleaf Forest

Evergreen Broadleaf Forest

Evergreen Needleleaf Forest

Mixed Forest

Water Bodies

Herbaceous Wetland

Wooded Wetland

Barren or Sparsely Vegetated

Herbaceous Tundra

Wooded Tundra

Mixed Tundra

Bare Ground Tundra

Snow or Ice

Playa

Lava

White Sand

SOIL TYPE CLASS

SAND

LOAMY SAND

SANDY LOAM

SILT LOAM

SILT

LOAM

SANDY CLAY LOAM

SILTY CLAY LOAM

CLAY LOAM

SANDY CLAY

SILTY CLAY

CLAY

ORGANIC MATERIAL

WATER

BEDROCK

OTHER(land-ice)

PLAYA

LAVA

WHITE SAND

ANALYSIS CHANGES

The Eta 3DVAR code has been modified to use the NEXRAD Level 2.5 radial wind data, and
a 2dvar module is now run to analyze surface temperature data